JP3164890B2 - Quartz crystal resonator and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and a manufacturing method of a small and highly stable crystal unit.

[0002]

2. Description of the Related Art Quartz resonators have high stability
It is used as an important device indispensable for information communication. With the recent development of satellite communications and mobile phones,
One of the major goals is miniaturization and high performance of each device, but crystal oscillators are no exception.

As a conventional quartz oscillator, there is one in which an AT-cut quartz plate is supported by a metal supporting frame. FIG. 7 shows an example of these crystal units. In FIG. 7, 18
Denotes an AT-cut quartz plate, 3 denotes electrodes deposited on both sides of the quartz plate 1, 19 denotes a holding portion for holding the quartz plate 18, and 20 denotes a holding portion for bonding the holding portion 19 and the quartz plate 18. It is a conductive adhesive. The electrodes 3 are electrically connected to different holding portions via a conductive adhesive.

In a conventional quartz oscillator, a metal holding portion 19 and a conductive adhesive 20 are usually used to hold a quartz plate. However, when a metal holding part is used, the thermal expansion coefficient is different from the thermal expansion coefficient of quartz, so that when the temperature of the crystal unit changes, thermal stress is generated between the holding part and the crystal. Since the oscillation frequency of the crystal plate greatly depends on the stress in the crystal, such a holding method results in a crystal resonator that is unstable with respect to temperature changes. Therefore, a structure is adopted in which a large space is provided between the electrode portion and the holding portion so that no stress is applied to the vibrating portion of the quartz plate. In addition, since conductive adhesive is used, stress due to the expansion and contraction of the adhesive during bonding is applied to the crystal, thermal stress is generated due to the difference in the coefficient of thermal expansion between the adhesive and the crystal, and the bonding strength is sufficient. Required that a large bonding area be used, the conductive adhesive has a problem with the heat resistance, so that only low-temperature processing can be performed during soldering, the release of gas accompanying the curing of the conductive adhesive, and mechanical vibration However, the stability of the crystal unit is degraded due to the fact that the crystal unit is not sufficiently stable and the problem of the deterioration of the adhesive. Although there is a method of using other various adhesives instead of the conductive adhesive, this problem is basically not solved as long as the adhesive is used.

FIG. 8 shows an example of a manufacturing process of the quartz oscillator. In this manufacturing process, the quartz plate is cut first, and then the individually cut quartz plate is polished. For this reason, when a quartz plate is cut into small pieces in order to produce a small quartz oscillator, a very small quartz plate is handled in the polishing step. In order to polish such a minute quartz plate, an advanced polishing apparatus must be used. For this reason, it is difficult to use this manufacturing method to accurately produce a smaller crystal resonator. Next, an electrode is vapor-deposited on the cut vibrating part and is connected to the holding part 19. At this time, it is necessary to handle the cut quartz plates individually, and to apply a conductive adhesive, a certain size or more is required. After that, the frequency is adjusted and hermetically sealed with a metal package. Due to the above-mentioned reasons relating to cutting and polishing, and the reason relating to the conductive adhesive, a crystal plate having such a structure usually has a high stability unless the quartz plate has a width of 2 mm or more and a length of 5 mm or more. It was difficult to make a crystal oscillator. In addition, since the quartz plate itself is large and must be separately mounted in a container for hermetic sealing, a considerable size is required for the entire quartz resonator.

In order to solve the problem of the thermal stress of the holding portion,
For example, Japanese Patent Laid-Open Publication No. 02-261210 describes a structure in which a quartz plate for vibration is held by a quartz plate having substantially the same thermal expansion. FIG. 9 shows this example.

In FIG. 9, reference numeral 21 denotes a vibrating crystal blank;
Are excitation electrodes deposited on both sides of the vibrating quartz piece 21;
Denotes a holding crystal piece for holding the vibration crystal piece 21;
4 is a base, 25 is a vibrating crystal blank 21 and a holding crystal blank 23
Is an adhesive for bonding the holding crystal piece 23 and the base 24. The direction in which the vibrating crystal blank 21 and the holding crystal blank 23 are fixed (the XX direction) is perpendicular to the direction in which the holding crystal blank 23 and the base 24 are fixed (ZZ). In this case, the longitudinal direction of the holding crystal piece 23 becomes a free end, and is free of stress due to expansion and contraction with respect to heat. Further, the vibrating crystal blank 21 is fixed at both ends so that the longitudinal direction coincides with the same direction of the crystal blank 23. Therefore, the expansion and contraction of the vibrating crystal piece 21 in the longitudinal direction is affected by the holding crystal piece 23, but the same material has the same thermal expansion coefficient and no thermal stress occurs. By doing so, a frequency change due to thermal expansion is prevented, and good temperature characteristics are obtained. However, since the vibration crystal piece 21 and the holding crystal piece 23 are fixed using a conductive adhesive, various problems caused by the conductive adhesive, stress due to expansion and contraction of the adhesive at the time of bonding, and the like. Problems with quartz, the problem of thermal stress due to the difference in the coefficient of thermal expansion between the adhesive and the quartz, the problem of insufficient bonding strength and the need for a large bonding area, and the problem of heat resistance of the conductive adhesive Therefore, the problems of only being able to be processed at a low temperature in soldering, release of gas due to hardening of the conductive adhesive, not being sufficiently stable against mechanical vibration, and deterioration of the adhesive are not solved. Therefore, this crystal resonator cannot have sufficient stability in terms of temperature characteristics and deterioration.

[0008]

In the conventional crystal unit, the thermal stress caused by the difference in the coefficient of thermal expansion between the quartz plate and the holding portion makes the oscillation frequency unstable and bonds the quartz plate and the holding portion. The problem is that the stress caused by the expansion and contraction of the adhesive during bonding is applied to the crystal due to the conductive adhesive used for bonding, the thermal stress is generated due to the difference in the coefficient of thermal expansion between the adhesive and the crystal, and the bonding strength is sufficient. Is not sufficient, a large bonding area is required, only heat treatment at low temperature is possible due to the problem of heat resistance of the conductive adhesive, gas release accompanying curing of the conductive adhesive, mechanical However, there is a problem that the adhesive is not sufficiently stable against mechanical vibration, and further, there is a problem of deterioration of the adhesive, and the characteristics are unstable with respect to temperature and mechanical vibration.

Further, in order to avoid interaction between the holding portion and the vibrating portion of the crystal and to ensure workability in the manufacturing process at the time of bonding, the crystal plate needs to have a size of several mm square or more. Was. Further, in consideration of hermetically sealing the quartz plate, the size of the whole quartz oscillator is further increased.

The present invention overcomes the above-mentioned drawbacks of the quartz oscillator, and enables the manufacture of a small, highly stable quartz oscillator.

[0011]

In order to solve the above-mentioned problems, a first quartz-crystal vibrator of the present invention comprises a main unit in which excitation electrodes face each other.
A quartz crystal plate for vibration formed on the
And a holding quartz plate to provide a sharp vibration space.
Serial one end of the vibrating quartz plate directly on the surface of the holding quartz plate
The direct bonding is at least one of the intermolecular force of hydroxyl group and hydrogen attached to the surface of each quartz plate, or the direct bond between silicon and oxygen which are constituent elements of each quartz plate. It is characterized by joining by one side. The second crystal oscillator of the present invention, are
In addition, the crystal unit base made of quartz and the crystal unit cover made of quartz are used as the intermolecular force of hydroxyl group and hydrogen attached to the surface of each quartz plate, or a constituent element of each quartz plate. The crystal unit is sealed inside the base and the lid by directly bonding at least one of a direct bond between silicon and oxygen. The manufacturing method of the first crystal oscillator of the present invention, beforehand
The surface of the vibrating quartz plate with electrodes formed on one side and the surface of the holding quartz plate are subjected to hydrophilic treatment to attach hydroxyl groups to the surfaces and contact them. By heat treatment, the vibration quartz plate is directly joined to the holding quartz plate, and then the electrode is
An electrode is formed on the other surface of the formed quartz plate for vibration .

[0012]

[Function] By using direct bonding, a mechanically strong and non-deteriorating bonding method is provided, and the difference in the coefficient of thermal expansion between the vibrating part and the holding part is minimized by holding the quartz plate using the quartz plate. The generation of thermal stress due to the difference in the coefficient of thermal expansion is suppressed, the oscillation frequency of the crystal resonator is prevented from being changed, and the crystal resonator is manufactured using a simple and suitable manufacturing process for miniaturization. It can be manufactured at low cost.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows the structure of a quartz oscillator according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a vibrating quartz plate, 2 denotes a holding quartz plate, 3 denotes a pair of excitation electrodes deposited on both surfaces of the vibrating quartz plate 1, and 4 denotes an electric connection between the excitation electrode 3 and the outside. It is an electrode take-out part for electrical connection. The vibrating quartz plate 1 and the holding quartz plate 2 are bonded by a direct joining technique. In direct bonding, crystals are directly bonded to each other without using an adhesive. In the conventional crystal unit, thermal stress was generated due to the difference in the thermal expansion coefficient between the crystal and the holding unit, and the stability of the crystal unit was impaired.
In this embodiment, since the quartz crystal having the same thermal expansion coefficient is used for both the holding section and the vibrating section, the problem of thermal stress due to the difference in the thermal expansion coefficient between the vibrating section and the holding section does not occur. Furthermore, since the bonding between the holding part and the vibrating part is performed directly without using an adhesive, the generation of thermal stress due to the difference in the coefficient of thermal expansion between the adhesive of the crystal unit and the crystal, and long-term stability It also has excellent properties.

The temperature characteristic of the crystal unit is ideally determined by the cut angle of the crystal plate. For example, in the case of an AT-cut quartz resonator, ± 5pp in a temperature range of -20 ° C to + 70 ° C.
m. However, in an actual crystal resonator, the temperature characteristics are worse than those in the theoretical state because of the influence of the holding portion. In the present embodiment, a quartz plate having a long side of 3 mm and a short side of 1 mm with an excitation electrode deposited thereon was used as a vibrating quartz plate. When the stability of the crystal unit was measured using the vibration quartz plate in the conventional structure and the case using the structure of the present embodiment and using the direct bonding technology, the stability of the quartz oscillator was measured. In the case of a quartz oscillator with the structure of
An improvement in pm was seen. This is because the holding portion is made of quartz having the same coefficient of thermal expansion and no adhesive is used, so that no thermal stress is generated due to the difference in the coefficient of thermal expansion between the adhesive and the quartz. In addition, in the present example that does not use an adhesive even in long-term stability, it shows a very high stability result,
The problem of stress on the crystal due to the expansion and contraction of the adhesive during bonding,
It can be seen that the conductive adhesive is not sufficiently stable against gas release and mechanical vibration accompanying the curing of the conductive adhesive, and furthermore, the problem of deterioration of the adhesive did not occur. In this case, a quartz plate with a long side of 3 mm and a short side of 1 mm was used. However, the structure of the present embodiment is more stable than a crystal unit using a conventional holding method even in a smaller crystal unit. It is clear that a perfect crystal resonator can be obtained. Furthermore, since no adhesive is used, the problem of the heat resistant temperature of the adhesive, which is present in the conventional vibrator, does not occur at all, so that solder reflow is also possible.

Also, in this embodiment, the difference between the thermal expansion coefficients of the holding portion and the vibrating portion is minimized by joining the quartz crystal plate for vibration 1 and the quartz crystal plate for holding 2 having the same cut angle and the same joint surface. . In particular, when the cut angle and the joining surface completely match, no thermal stress is generated. At this time, it is clear from the effect of the present embodiment that the temperature characteristics of the crystal resonator become the best.

(Embodiment 2) FIG. 2 shows the structure of a quartz oscillator according to a second embodiment of the present invention. FIG. 2A is a sectional view thereof,
(B) is a perspective view of the inside of the housing, and (c) is an overall perspective view. FIG.
In the figures, 1 is a vibrating quartz plate, 3 is an exciting electrode deposited on both sides of the vibrating quartz plate 1, 4 is a lead portion of the exciting electrode, 5 is a quartz oscillator base made of quartz, and 6 is A quartz oscillator lid portion made of quartz, 7 is an external electrode, and 8 is a low-melting glass for drawing the external electrode out of the quartz oscillator. In this embodiment, the vibrating quartz plate 1 and the crystal resonator base 5 having a concave portion at the center, and the crystal resonator base 5 and the crystal resonator lid 6 having a concave portion at the center are directly connected to each other. After bonding, the electrode lead-out portion 7 is sealed with low-melting glass to hermetically seal the inside of the crystal unit. For this reason, the vibrating quartz plate 1 is adhered to a material other than quartz, so that the vibrating quartz plate 1 is not subjected to thermal stress. In addition, by drawing out the excitation electrode to the outside through the low melting point glass 8, a structure in which no adhesive is present inside the crystal unit is obtained.

The temperature characteristic of the crystal unit is ideally determined by the cut angle of the crystal plate. For example, in the case of an AT-cut quartz resonator, ± 5pp in a temperature range of -20 ° C to + 70 ° C.
m. However, in an actual crystal resonator, the temperature characteristics are worse than those in the theoretical state because of the influence of the holding portion. A comparison is made between the case of a conventional crystal unit in which excitation electrodes are deposited on a vibration crystal plate having a long side of 3 mm and a short side of 1 mm, and the crystal unit of the present embodiment using a vibration crystal plate of the same dimensions. A 15 ppm improvement in temperature characteristics was observed. This is because a quartz oscillator base using quartz having the same coefficient of thermal expansion is used as the holding part, and no thermal stress is generated due to a difference in coefficient of thermal expansion between the adhesive and the crystal because no adhesive is used. That's why. In addition, even in the long-term stability, the present example in which an adhesive is not used shows a very high stability result, the stress caused by the expansion and contraction of the adhesive at the time of bonding is applied to the crystal, and the gas accompanying the curing of the conductive adhesive It can be seen that there is no problem that the adhesive is not sufficiently stable against the release and mechanical vibration, and that the adhesive does not deteriorate. Further, the dimensions of the entire crystal unit are 6 mm long and 4 mm short sides including the holding unit and the housing in the conventional crystal unit, whereas the size of the crystal unit in this embodiment is Is long side 4.5
Although a quartz crystal plate for vibration having the same size as a millimeter and a short side of 2.5 mm is used, the crystal resonator is small. This is because the space required for applying the adhesive was reduced to a small space by using direct bonding, and the conventional method was accompanied by the occurrence of thermal stress due to the difference in coefficient of thermal expansion. A gap was required between the bonded part and the vibrating part to reduce the change in the oscillation frequency.However, in the crystal resonator of this embodiment, thermal stress was not generated because the crystal was directly bonded to each other. This is because a gap is no longer necessary. In this case, a quartz plate with a long side of 3 mm and a short side of 1 mm was used. However, the structure of the present embodiment is more stable than a crystal unit using a conventional holding method even in a smaller crystal unit. It is clear that a perfect crystal resonator can be obtained. Furthermore, since no adhesive is used, the problem of the heat resistant temperature of the adhesive, which is present in the conventional vibrator, does not occur at all, so that solder reflow is also possible.

(Embodiment 3) FIG. 3 shows an embodiment of a method of manufacturing a quartz oscillator having the structure of the present invention. In FIG. 3, 1 is a quartz plate for vibration, 2 is a quartz plate for holding, 3 is an excitation electrode,
Is an extraction electrode, 9 is a vibrating quartz plate, 10 is an exciting electrode deposited on the lower surface of the vibrating quartz plate 1, 11 is a holding quartz plate, and 12 is a deposited on the lower surface of the vibrating quartz plate 1. An excitation electrode and a lead electrode that is simultaneously deposited. FIG. 3A shows the structure of the crystal resonator manufactured according to this embodiment, and FIGS. 3B to 3G show the manufacturing steps.

In this embodiment, the quartz plates 9 and 11 are AT-cut quartz plates having a thickness of 350 μm and a size of 3 inches.

The vibrating quartz plate 9 is a vibrating quartz plate 1.
Is etched away to a depth of 80 μm while leaving a large number of shapes, and one excitation electrode 10 is formed on the vibrating crystal plate 9 by vacuum evaporation. In this embodiment, chromium was formed to a thickness of 0.1 μm and gold was formed to a thickness of 2 μm by vacuum deposition. This is shown in FIG. FIG. 3C shows the state of the holding crystal element plate 11. The contact portion between the quartz crystal plate 11 and the quartz crystal plate 9 is polished to a mirror surface, the surface is hydrophilized using a solution obtained by heating a mixed solution of ammonia water, hydrogen peroxide water and water at 60 ° C., and washed with water. did. Thereafter, the plate was carefully washed so that no dust was present in a portion where the vibrating quartz plate 1 and the holding quartz plate 2 were in contact with each other. Next, the quartz plate 9 and the quartz plate 11 were brought into contact with each other while keeping the surface clean. This state is shown in FIG.
(D). Although there is considerable adhesive strength even in this state, a heat treatment was performed to increase the adhesive strength to a level at which polishing can be performed later. In addition, the crystal transition temperature of quartz is 8
Since the temperature is 70 ° C., the heat treatment temperature cannot be increased above this temperature. Therefore, in the present embodiment, the heat treatment temperature was set to 500 ° C.

In direct bonding, the substrates are adsorbed to each other by an intermolecular force such as a hydroxyl group or hydrogen attached to the surface of each substrate by a hydrophilic treatment, and a hydroxyl group or the like is gradually removed from the bonding interface by a subsequent heat treatment. Accompanying
It is considered that the bond between silicon and oxygen, which are constituent elements of each crystal, is strengthened. Therefore, the bonding strength increases as the heat treatment temperature increases. Actually, heat treatment at 100 ° C. was effective. On the high temperature side, the crystal transition temperature of quartz was the limit. In this example, the heat treatment was performed at 500 ° C., but the heat treatment could be performed at a higher temperature as long as the temperature was lower than the crystal transition temperature.

In order to separate the vibrating quartz plates 1 one by one, the quartz plate 9 directly joined to the quartz plate 11 was polished while holding the quartz plate 11. This state is shown in FIG.

The excitation electrode 12 is formed by vacuum evaporation from the side where the vibration crystal plate 1 is joined to the quartz crystal plate 9 substantially at the center of the vibration crystal plate 1.
This state is shown in FIG.

Finally, the quartz crystal plates 11 were cut off one by one to obtain a quartz oscillator. This state is shown in FIG.

The vibrating quartz plate 1 is hardly subjected to stress due to heat, so that a change in frequency due to a stress caused by a temperature change can be suppressed very small, and the frequency stability is improved. Further, since an adhesive is not required for fixing, stability and reliability against heat and vibration are improved. Further, since the dimensions of the vibrating quartz plate 1 and the quartz holder 2 are very precisely processed by applying a semiconductor processing technique such as photolithography or etching, the size is very small and the precision is high. , And a high-performance quartz oscillator can be obtained.

(Embodiment 4) FIG. 4 shows a third embodiment of the crystal unit according to the present invention. In FIG. 4, 1 is a quartz crystal plate for oscillation, 2 is a quartz crystal plate for holding, 3 is an excitation electrode, 4 is a lead-out portion of the excitation electrode, 13 is a housing or substrate of the quartz oscillator,
Reference numeral 14 denotes an external electrode for exciting the excitation electrode. The vibrating quartz plate 1 and the holding quartz plate 2 are joined by direct joining. Further, the holding quartz plate 2 has a long and thin rod shape, and has a structure in which stress from the substrate 5 is not easily transmitted to the vibrating quartz plate 1. As a material of the substrate 5, a ceramic substrate or the like is used. However, since the coefficient of thermal expansion differs between the quartz and the ceramic substrate, when the temperature changes, thermal stress is generated at the joint between the substrate 5 and the holding quartz plate 2. When this thermal stress is applied to the vibrating quartz plate 1, the oscillation frequency changes and stable oscillation cannot be performed. In this embodiment, since the vibrating quartz plate 1 is held by using the holding quartz plate 2, no thermal stress is generated between the vibrating quartz plate 1 and the holding quartz plate 2. Although thermal stress is generated between the holding quartz plate 2 and the substrate 5, the stress is not applied to the vibrating quartz plate 1 because the holding quartz plate 2 has an elongated rod shape. The vibrating quartz plate 1 can stably oscillate without being affected by thermal stress. Further, since the vibrating quartz plate 1 and the holding quartz plate 2 are joined by direct joining, they are excellent in mechanical rigidity and long-term stability, and can be processed in a small size and easily. ing.

The temperature characteristic of the crystal resonator is ideally determined by the cut angle of the crystal plate. For example, in the case of an AT-cut quartz resonator, ± 5pp in a temperature range of -20 ° C to + 70 ° C.
m. However, in an actual crystal resonator, the temperature characteristics are worse than those in the theoretical state because of the influence of the holding portion. In this example, a ceramic substrate was used as the substrate 5 and a quartz plate having a long side of 3 mm and a short side of 1 mm with an excitation electrode deposited thereon was used as the vibrating quartz plate. The stability of the crystal unit between the case where a crystal unit with the conventional structure is made using this crystal plate for vibration and the case where the crystal unit with the structure of this embodiment is made using the direct bonding technology As a result, the temperature characteristic of the quartz resonator having the structure of the present example was improved by 10 ppm. This is because the holding portion is made of quartz having the same coefficient of thermal expansion and no adhesive is used, so that no thermal stress is generated due to the difference in the coefficient of thermal expansion between the adhesive and the quartz. In addition, even in the long-term stability, the present example in which an adhesive is not used shows a very high stability result, the stress caused by the expansion and contraction of the adhesive at the time of bonding is applied to the crystal, and the gas accompanying the curing of the conductive adhesive It can be seen that there is no problem that the adhesive is not sufficiently stable against the release and mechanical vibration, and that the adhesive does not deteriorate. In this case, a quartz plate with a long side of 3 mm and a short side of 1 mm was used. However, the structure of the present embodiment is more stable than a crystal unit using a conventional holding method even in a smaller crystal unit. It is clear that a perfect crystal resonator can be obtained. Furthermore, since no adhesive is used, the problem of the heat resistant temperature of the adhesive, which is present in the conventional vibrator, does not occur at all, so that solder reflow is also possible.

In the present embodiment, the holding quartz plate 2 is formed in an elongated rod shape. However, a quartz plate having a structure in which the thermal stress generated between the holding quartz plate 2 and the substrate 5 is hardly transmitted to the vibrating quartz plate 1. Clearly, the same effect can be obtained. Further, although the ceramic substrate is used as the substrate 5, it is apparent that the effect of the present embodiment is not impaired by not only the ceramic substrate but also any other substrate.

Further, in this embodiment, the difference between the thermal expansion coefficients of the holding portion and the vibrating portion is minimized by joining the quartz crystal plate for vibration 1 and the quartz crystal plate for holding 2 having the same cut angle and the same joint surface. . In particular, when the cut angle and the joining surface completely match, no thermal stress is generated. At this time, it is clear from the effect of the present embodiment that the temperature characteristics of the crystal resonator become the best.

(Embodiment 5) FIG. 5 is a sectional view showing a crystal resonator according to Embodiment 4 of the present invention. In FIG. 5, 1
Is a quartz plate for vibration, 2 is a quartz plate for holding, 3 is an electrode for excitation,
Reference numeral 4 denotes an excitation electrode lead portion, reference numeral 15 denotes a base portion of the crystal resonator housing, reference numeral 16 denotes a cover portion of the crystal resonator housing,
Is a low-melting glass that joins the cover and base of the housing. The vibrating quartz plate 1 and the holding quartz plate 2 are directly joined. The excitation electrodes 3 deposited on both surfaces of the vibrating quartz plate 1 are drawn out of the quartz resonator through the drawer 4 and the low melting point glass 7. In this embodiment, since the vibration crystal plate 1 and the holding crystal plate 2 are formed using the direct bonding technique, a small-sized vibration crystal plate can be manufactured at low cost. For this reason, it is possible to use a very small case for the case that encloses the crystal plate, and the overall size of the crystal unit is 2 mm or less compared to the conventional several mm square. A vibrator can be created. Further, since the vibrating quartz plate 1 and the holding quartz plate 2 for holding the same are made of the same material,
No thermal stress is generated between the two, so that a very stable crystal resonator can be manufactured.

FIG. 6 is a sectional view of a conventional crystal unit in which crystal is directly bonded to a ceramic substrate. 1 is a quartz crystal plate for vibration, 3 is an electrode for excitation, 4 is a lead electrode, 15 is a base portion of the quartz oscillator housing, 16 is a cover portion of the quartz oscillator housing, 1
7 is a low-melting glass for joining the cover and the base of the housing, 1
Reference numeral 8 denotes a conductive adhesive for joining the vibration crystal plate 1 and the housing base. The excitation electrodes 3 deposited on both surfaces of the vibrating quartz plate 1 are drawn out of the quartz resonator through the lead portion 4 and the conductive adhesive 18, and through the low melting point glass 7.

The temperature characteristic of the crystal unit is ideally determined by the cut angle of the crystal plate. For example, in the case of an AT-cut quartz resonator, ± 5pp in a temperature range of -20 ° C to + 70 ° C.
m. However, in an actual crystal resonator, the temperature characteristics are worse than those in the theoretical state because of the influence of the holding portion. In the present embodiment, a quartz plate having a long side of 3 mm and a short side of 1 mm with an excitation electrode deposited thereon was used as a vibrating quartz plate. The stability of the crystal unit between the case where a crystal unit with the conventional structure is made using this crystal plate for vibration and the case where the crystal unit with the structure of this embodiment is made using the direct bonding technology As a result, the temperature characteristic of the quartz resonator having the structure of the present example was improved by 10 ppm. This is because the holding portion is made of quartz having the same coefficient of thermal expansion and no adhesive is used, so that no thermal stress is generated due to the difference in the coefficient of thermal expansion between the adhesive and the quartz. In addition, even in the long-term stability, the present example in which an adhesive is not used shows a very high stability result, the stress caused by the expansion and contraction of the adhesive at the time of bonding is applied to the crystal, and the gas accompanying the curing of the conductive adhesive It can be seen that there is no problem that the adhesive is not sufficiently stable against the release and mechanical vibration, and that the adhesive does not deteriorate. In this case, a quartz plate with a long side of 3 mm and a short side of 1 mm was used. However, the structure of the present embodiment is more stable than a crystal unit using a conventional holding method even in a smaller crystal unit. It is clear that a perfect crystal resonator can be obtained. Furthermore, since no adhesive is used, the problem of the heat resistant temperature of the adhesive, which is present in the conventional vibrator, does not occur at all, so that solder reflow is also possible.

Further, in this embodiment, the long side is 3 mm,
Although a quartz plate with a short side of 1 mm was used, it is possible to create a smaller crystal unit by using the direct bonding technology.
It is clear that the structure is more suitable for miniaturization than the structure of a conventional crystal unit.

In the present embodiment, the electrode material has a two-layer structure of gold and chromium. However, it is apparent that the same effect can be obtained by using either one of the single-layer structures. Further, it is clear from the effect of the present embodiment that the same effect is obtained even if the material is other than gold or chromium, or if the electrode has a multilayer structure.

In this embodiment, the difference between the thermal expansion coefficients of the holding portion and the vibrating portion is minimized by joining the quartz crystal plate for vibration 1 and the quartz crystal plate for holding 2 having the same cut angle and the same joint surface. . In particular, when the cut angle and the joining surface completely match, no thermal stress is generated. At this time, it is clear from the effect of the present embodiment that the temperature characteristics of the crystal resonator become the best.

Finally, the effects in the above embodiment are attributable to the fact that no inorganic or organic adhesive is involved between the vibrating quartz plate and the holding quartz plate, that is, they are joined by direct joining. It is clear that the above-mentioned effects are obtained regardless of the size and cut angle of the quartz plate, the size of the quartz plate, and the type of the vibrating quartz resonator, and irrespective of the electrode structure.

[0038]

As is clear from the above embodiments, the present invention provides a method for manufacturing a crystal plate and a holding plate in which the thermal stress caused by the difference in the thermal expansion coefficient between the quartz plate and the holding portion does not make the oscillation frequency unstable. The problem of stress caused by the expansion and contraction of the adhesive during bonding due to the conductive adhesive used to bond the parts to the crystal, and the problem of thermal stress being generated due to the difference in the coefficient of thermal expansion between the adhesive and the crystal. That the adhesive strength is not sufficient and that a large bonding area is required, that the conductive adhesive has a problem with the heat resistance, and that only soldering can be performed at a low temperature, It is not sufficiently stable against release and mechanical vibration, and there is no problem such as adhesive deterioration, unstable characteristics against temperature and mechanical vibration, and more suitable for miniaturization Highly stable crystal oscillator can be manufactured And it serves as a.

[Brief description of the drawings]

FIG. 1 is a perspective view of a crystal unit according to a first embodiment of the present invention.

2A is a cross-sectional view of a crystal unit according to a second embodiment of the present invention. FIG. 2B is a diagram showing the inside of a housing of the crystal unit. FIG. 2C is a perspective view of the crystal unit.

3A is a perspective view of a crystal unit according to a third embodiment of the present invention, FIG. 3B is a diagram illustrating a method of manufacturing the crystal unit, and FIG. 3C is a diagram illustrating a method of manufacturing the crystal unit. FIG. 4D shows a method for manufacturing the same crystal resonator. FIG. 6E shows a method for manufacturing the same crystal resonator. FIG. 6F shows a method for manufacturing the same crystal resonator. Diagram showing child manufacturing method

FIG. 4 is a perspective view of a crystal resonator according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a crystal unit according to a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a conventional crystal unit.

FIG. 7 is a perspective view of a conventional crystal unit.

FIG. 8 is a manufacturing process diagram of a conventional crystal unit.

FIG. 9 is a perspective view of a conventional crystal unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vibrating crystal plate 2 holding crystal plate 3 excitation electrode 4 electrode take-out part 5 crystal resonator base 6 crystal resonator lid 7 external electrode 8 low melting point glass 9 vibration crystal plate 10 excitation electrode 11 holding Quartz blank 12 Electrode for excitation and extraction electrode 13 Quartz resonator housing or substrate 14 External electrode 15 Quartz resonator housing base 16 Quartz resonator housing cover 17 Low melting point glass 18 AT cut quartz plate 19 Holder 20 Conductive adhesive 21 Quartz piece for vibration 22 Excitation electrode 23 Quartz piece for holding 24 Base 25 Conductive adhesive 26 Adhesive

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yutaka Taguchi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-63-285195 (JP, A) JP-A-63-82116 (JP, A) JP-A-2-183510 (JP, A) JP-A-1-246820 (JP, A) JP-A-62-122148 (JP, A) JP-B-57-46034 (JP, B2) JP-T4-502984 (JP, A)

Claims (3)

(57) [Claims] An excitation electrode formed on a main surface facing an excitation electrode.
Provide an appropriate vibration space to the working quartz plate and the vibrating quartz plate.
And a holding quartz plate for obtaining the vibration quartz plate.
One end is directly bonded and held to the surface of the holding quartz plate.
The direct bonding is performed by at least one of the intermolecular force of hydroxyl groups and hydrogen attached to the surface of each quartz plate, or the direct bond between silicon and oxygen, which are constituent elements of each quartz plate. A quartz oscillator characterized by being provided. 2. The quartz resonator according to claim 1, which is made of quartz.
Crystal on the base of the crystal unit
The vibrator lid is formed from the base part of the crystal unit and the intermolecular force of hydroxyl group or hydrogen attached to the surface of each crystal plate, or the direct bond between silicon and oxygen which are constituent elements of each crystal plate. A crystal unit, wherein the crystal unit is sealed inside the base unit and the lid unit by directly bonding at least one of the units. 3. The surface of the vibrating quartz plate and the holding quartz plate having electrodes formed on one surface in advance is subjected to hydrophilic treatment so that hydroxyl groups are adhered to the surfaces and brought into contact with each other. By performing a heat treatment within a temperature range in which the quartz crystal exhibits piezoelectricity, the vibrating quartz plate is directly joined to the holding quartz plate, and then the other of the vibrating quartz plate on which the electrodes are formed.
Forming an electrode on the surface of the crystal resonator.